This invention relates to, e.g., a printer, an image output apparatus which includes the printer and a method of controlling the apparatus. More particularly, the invention relates to an image output apparatus adapted to cope with a case in which a fatal error occurs when an image is formed, and to a method of controlling this apparatus.
In addition to single-function printers, there have been proposed multifunction apparatus equipped with an image reading function such as that of an image scanner and a facsimile communication function, whereby a single apparatus provides a plurality of image input/output functions such as a copy function, facsimile function and printing function.
If data described in page description language (referred to as “PDL data” below) is input when such a printer or multifunction apparatus is used as an image output apparatus, often an image is formed and output on the basis of this data. If a fatal error occurs in such an image output apparatus owing, say, to the inclusion of a command that cannot be interpreted in the entered PDL data, it is proposed to shut down all functions from the moment the error occurs, notify the user of this fact and warn the user so that the user will turn the main power supply off and on.
If the above-described fatal error occurs in a multifunction apparatus having multiple image input/output functions, the main power supply must be turned off and on in order to recover from the error. This means that if another function is being executed concurrently with the function in which the error occurred, this other function also is suspended by turning off the main power supply. For example, assume an instance where printing processing develops a fatal error, e.g., an error in which a command that cannot be interpreted is received, when the reception and printing of PDL data are being executed in parallel with facsimile reception. If the main power supply is not shut down in such case, recovery of the printing function will not take place. The problem is that facsimile reception also must be interrupted.